1. Field of the Invention
The present invention relates to a blood suction device which is used at a surgical site for drainage of pooled blood in order to keep the operating field clear of blood and thus visible to the surgeon, and in which hemolysis, infection, clotting and other undesirable effects upon blood can fully be eliminated.
2. Description of the Prior Art
Blood suction devices are extensively used in such medical procedures as cardiotomy operations for keeping the operating field clear of blood and thus visible to the surgion, and the sucked blood is usually re-infused to the patient during or after the operation. The known blood suction device has a suction tip and a roller pump communicating with the tip by a length of flexible tubing through which blood is conveyed. The roller pump is commonly positioned remotely from the surgical field at a pump-oxygenator which is used for controlling circulation and oxygenation of the blood bypassed from the heart. A typical perfusion system is shown in FIG. 1 in order to more fully understand the present invention. The venous return from ascending and descending vena cava is introduced to an oxygenator 1 through tubes 2, 3 by means of gravity venous drainage. The blood is oxygenated at the oxygenator 1 and then re-infused to an aorta and a femoral artery through pumping tubes 4, 5 which are subjected to occlusion by means of a roller pump 6. The blood which may accumulate within the heart is removed by venting thereof by means of a roller pump 7 and then is conveyed through a cardiotomy return reservoir 8 to the oxygenator 1, and also is re-infused to the aorta and the femoral artery. The pump-oxygenator units are used in many of the major surgical procedures in which a blood suction device is essential for keeping the operating field clear of blood and visible to the surgeon. Thus, conventionally one or more, illustratively two in FIG. 1, of the blood suction devices are used in the perfusion system.
Each of the known blood suction devices comprises respectively suction tips 9, 10, pumping tubes 11, 12 communicating with the suction tips 9, 10 for drainage of the pooled blood, and roller pumps 13, 14 engaging with the pumping tubes 11, 12 for occlusion thereof. The ends of the pumping tubes 11, 12 are connected to the cardiotomy return reservoir 8 so that the blood may be re-infused in a similar manner as described above to the patient during or after the operation. These conventional blood suction devices have been found not entirely satisfactory, however, in that, since the surgical field is positioned remotely from the pump-oxygenator unit and other associated devices where the control of the blood suction devices are managed, the instructions given by the surgeon handling the blood suction tip at the surgical field can not reach the already overburdened pump technician in sufficient time for him to control the blood suction devices immediately. The time lag between the instructions and the real initiation of the control may cause the blood suction device to suck air which results in an increase of blood hemolysis, or may cause the blood suction device to suck blood too slowly to attain the drainage of the large amount of pooled blood in a short time. Thus, when the roller pumps 13, 14 operate without the suction tips 9, 10 being immersed in blood, a rush of air through the pumping tubes 11, 12 is generated so that a great deal of hemolysis, as well as clotting and other undesirable effects may occur.